[Viral therapy of cancer].

In spite of the advances achieved in cancer therapeutics, conventional therapies still face problems such as toxicity to normal tissues and low efficacy in advanced phases of the disease. One of the most recent options, albeit experimental, is gene therapy. This strategy shows higher specificity than conventional therapies, but the low efficiency of gene transduction is a hurdle yet to be overcome, and the clinical trials have not shown the expected efficacy. Recently, oncolytic viruses have revived as an alternative in the field of cancer therapeutics. By virtue of the advances in virology and molecular biology techniques, the manipulation of viral genomes to attenuate their pathogenicity and the modification of their life cycle to allow tumor specific viral replication are now possible. At the moment, adenovirus and herpes simplex type 1 mutants are the most commonly employed viruses. Recent clinical trials using these mutant viruses have shown safety and efficacy. Moreover, viral therapy has been combined with radiotherapy or chemotherapy demonstrating additive antineoplastic effects. In this manuscript, we review the biology behind this therapy, the obstacles, and the ongoing clinical trials.